"Back then I was rapping for the hell of it/ Right now I'm rapping to stay relevant." So says B.o.B on Aeroplanes, outlining precisely the problem with his debut album. A protege of T.I. and beneficiary of internet hype thanks to a series of smart, humorous mixtapes, Bobby Ray Simmons Jr now finds himself fronting a ruthless conspiracy to seize the wallets of teenage America. But all the Chris Martinesque piano lines and calibrated guest appearances – from Weezer's River Cuomo to Janelle Monáe – can't obscure an absence of soul throughout. For someone who raps so often about his days as an up-and-comer, there's a distinct lack of passion, too; this is all put into striking relief on the album's final verse, an incendiary performance from Eminem.